Field of the Invention
The present invention relates to a contact terminal and an IC socket including the same.
Description of the Related Art
A variety of semiconductor devices to be mounted on electronic devices and the like are subjected to various tests e.g. a burn-in test at a stage before being mounted, so as to eliminate potential defects therein. A semiconductor device socket made available for such a test is generally referred to as an IC socket, which is located either on a test board or a burn-in board serving as a printed wiring board.
As disclosed in Japanese Patent Application Laid-Open No. 2000-9752, No. 2003-297514, and No. 2008-77988, such an IC socket is provided with a plurality of contact terminals which electrically connect terminals of a semiconductor device to electrode portions of the aforementioned printed wiring board. As shown in Japanese Patent Application Laid-Open No. 2000-9752, for example, there is proposed a contact terminal used for a semiconductor device of a type to be embedded in a BGA (ball grid array)-type package as an object to be inspected, for instance, which comprises: a first contact piece provided with a first protrusion extending in a vertical direction; a second contact piece provided with a second protrusion and a third protrusion extending parallel to each other in the vertical direction with a predetermined interval; a coupling portion which couples a lower end of the first contact piece to a lower end of the second contact piece while bringing the first contact piece and the second contact piece face to face; and a fixation terminal portion connected to the coupling portion, which are configured to pinch each electrode portion in the semiconductor device at an appropriate position depending on the size of the diameter of the spherical electrode portion. Hereby, during a burn-in test, the first protrusion, the second protrusion, and the third protrusion bite into the spherical electrode portion in the semiconductor device by use of elastic forces of the first contact piece and the second contact piece, so that reliable electrical connection can be achieved between the contact terminal and the spherical electrode portion in the semiconductor device.
Moreover, as shown in Japanese Patent Application Laid-Open No. 2003-297514, for example, there is proposed a contact terminal used for a semiconductor device adopting a BGA-type package, in which protrusions of touch portions at tip ends of a pair of elastic contact pieces opposed to each other are formed in alignment with oblique straight lines tangential to a circle of a common circular cross section of a spherical electrode portion with which the protrusions come into contact, so as to avoid a situation that the pair of contact portions of the contact terminal can hardly be come off the spherical electrode portion in the semiconductor device after a test due to sticking of the contact portions to the spherical electrode portion. Herewith, the protrusions of the contact portions are reliably come off the spherical electrode portion, whereby a self-cleaning effect is achieved.
Furthermore, as shown in Japanese Patent Application Laid-Open No. 2008-77988, for example, there is proposed a contact terminal used for a semiconductor device adopting a BGA-type package, in which contact ends at contact point portions of a pair of movable pieces have slanted contact ends so as to pinch a maximum diameter portion of a spherical electrode portion.